1. Field of the Invention
The invention relates to high voltage semiconductor devices, and in particular, to lateral diffused metal oxide semiconductor (LDMOS) devices with electrostatic discharge (ESD) protection capability.
2. Description of the Related Art
In conventional integrated circuits, LDMOS transistors are vulnerable to high-voltage (HV) electrostatic discharge damage. This is mainly because the gate oxide layer of the LDMOS transistor is close to drain region, and further away from the source/body diffusion regions. Thus, when the ESD current travels from the drain end of the transistor, the energy of the ESD current tends to distribute towards the gate oxide layer, rather than flow towards the source/body diffusion regions, resulting in break down of the gate oxide.
In the conventional integrated circuits with HV devices, other additional ESD protection components are often adopted to avoid LDMOS transistor components from breaking down. However, the additional ESD protection components increase occupied space of the integrated circuit, and increase the complexity of fabrication thereof, resulting in higher manufacturing costs. Accordingly, a modified lateral diffused metal-oxide semiconductor transistor (LDMOS) device structure with excellent electrostatic discharge (ESD) protection capability is desired.